1. Field of the Invention
The present invention relates to an illumination optical apparatus including a fly-eye lens and a projection type display apparatus using the same.
2. Description of the Related Art
For example, an illumination optical apparatus used in a projection type display apparatus (projector), etc. provided with a liquid crystal display device is configured to include a pair of fly-eye lenses.
In an illumination optical apparatus including a pair of fly-eye lenses, the pair of fly-eye lenses uniformize a light intensity distribution of an illumination light from a light source and irradiate to an illumination surface of, for example, a liquid crystal display panel as a spatial light modulation device, etc.
As an illumination optical apparatus of this kind, for example, an apparatus including a mirror for changing a direction of an illumination light has been proposed. (for example, refer to the Japanese Unexamined Patent Publication No. 7-161601).
There are a variety of sizes of image display devices in projection type display apparatuses using a reflection type display device, and TIR prisms and color separation/composition prisms having a variety of optical path lengths are used in accordance with a size of the image display device.
In this case, arrangements of optical elements are different, so that a case of an illumination optical apparatus has been individually developed when developing an illumination optical system in accordance with a change of the image display device and prism. Therefore, investments on the molds became enormous to be a burden on the development costs.
To solve the problem, there is known a method of designing a projection type display device as explained below.
The method is, in a projection type image display apparatus having a light source, image display device, illumination optical system, projection lens, and optical unit structure: the optical unit structure is provided with one kind selected from two kinds of image display devices having a different display size at the same aspect ratio while keeping a predetermined distance from the light source to the image display device to be approximately equal; and the illumination optical system is provided with at least one of a plurality of optical elements at a predetermined position, so that an illumination region by the illumination optical system on the image display device matches approximately with a display size of the image display in accordance with the provided image display device.
A case of the illumination optical system is used in common in this designing method by keeping the distance from the light source to the image display device and using an image display device having a different size but the same aspect ratio.
As a result, an illumination optical system and projection optical system corresponding respectively to image devices having different display area sizes can be formed by using a common optical unit structure.
According to the designing method of a projection type display apparatus explained above, however, in the case of an illumination optical system of, for example, three-plate digital micro mirror device (DMD), when using a DMD having a different screen aspect ratio and different screen size, optical path lengths and sizes of the color separation/composition prism and TIR prism are different, so that the illumination optical system case cannot be used in common.